1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a MOS type semiconductor device of a salicide (self-aligned silicide) structure.
2. Description of the Related Art
One example of a MOS type semiconductor device having a salicide structure has been described in Japanese laid-open Patent No. 1996-186085.
In this type of semiconductor device, a silicide film has been selectively formed on the upper surface of a gate electrode and the surface of each diffusion layer. As a result, the resistance of the diffusion layer and the resistance of the gate electrode used as a wiring are reduced. This greatly contributes to the speeding up of the semiconductor device and an improvement in its performance. As silicides, a titanium silicide (TiSi2) and a cobalt silicide (CoSi2) are used.
Since the silicide on the surface of each diffusion layer is limited in its forming region by the gate electrode and spacers provided on its side surfaces, and arranged in line with the gate electrode, it is called “self-aligned silicide film, i.e., salicide film”.
However, there is a fear that the silicide excessively grows in a transverse direction at a portion below each spacer and hence the end of the silicide gets excessively close to the gate electrode abnormally, thus causing a leak current between the gate and the diffusion layer upon operation of the semiconductor device.